Asymptotic behavior of the warm inflation scenario with viscous pressure

Department of Physics, University of Lisbon, Lisboa, Lisbon, Portugal
Physical review D: Particles and fields (Impact Factor: 4.86). 12/2005; 73(2). DOI: 10.1103/PhysRevD.73.023502
Source: arXiv


We analyze the dynamics of models of warm inflation with general dissipative effects. We consider phenomenological terms both for the inflaton decay rate and for viscous effects within matter. We provide a classification of the asymptotic behavior of these models and show that the existence of a late-time scaling regime depends not only on an asymptotic behavior of the scalar field potential, but also on an appropriate asymptotic behavior of the inflaton decay rate. There are scaling solutions whenever the latter evolves to become proportional to the Hubble rate of expansion regardless of the steepness of the scalar field exponential potential. We show from thermodynamic arguments that the scaling regime is associated to a power-law dependence of the matter-radiation temperature on the scale factor, which allows a mild variation of the temperature of the matter/radiation fluid. We also show that the late time contribution of the dissipative terms alleviates the depletion of matter, and increases the duration of inflation. Comment: 31 pages, 2 figures, 3 tables. PACS numbers: 98.80Cq, 47.75+f

Download full-text


Available from: Jose Mimoso, Oct 23, 2012
  • [Show abstract] [Hide abstract]
    ABSTRACT: Scalar field models have been a focal point in cosmology during the last two decades or so. They play a central role in inflationary models, they arise in modified gravity theories that extend Einstein’s General Relativity (GR) which are, often, quantum motivated, and, recently, they have been put forward as a dark component of the universe. Here we analyse their dynamics in the framework of isotropic cosmologies presenting an unified approach that encompasses models both in Einstein’s GR and more general metric gravity theories. We perform a qualitative analysis of the major dynamical features of these models, discussing the existence of asymptotic regimes and their connection to a classification of the scalar fields potentials and couplings. A special interest is devoted to the interplay between scalar fields and matter which gives rise to scaling behaviour.
    No preview · Article · Jan 2011
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We provide a simple mathematical description of the exchange of energy between two fluids in an expanding Friedmann universe with zero spatial curvature. The evolution can be reduced to a single non-linear differential equation which we solve in physically relevant cases and provide an analysis of all the possible evolutions. Particular power-law solutions exist for the expansion scale factor and are attractors at late times under particular conditions. We show how a number of problems studied in the literature, such as cosmological vacuum energy decay, particle annihilation, and the evolution of a population of evaporating black holes, correspond to simple particular cases of our model. In all cases we can determine the effects of the energy transfer on the expansion scale factor. We also consider the situation in the presence of anti-decaying fluids and so called phantom fluids which violate the dominant energy conditions.
    Preview · Article · May 2006 · Physical review D: Particles and fields
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The decay of the inflaton into radiation and particles during the slow-roll suggests that these may interact with each other and that the latter may also decay into subproducts before inflation is completed. As a consequence, the fluid is no longer perfect and a non-negligible bulk viscosity necessarily sets in. We write the corresponding equations as an autonomous system and study the asymptotic behavior, the conditions for the existence of scaling solutions, and show that the late time effect of fluid dissipation alleviates the depletion of matter and increases the duration of inflation.
    Full-text · Article · Jan 2007
Show more